**2. Method**

LCA is an assessment tool for analyzing the environmental implication of process or product by taking cognizance of the potential effect of the entire cycle chain of such process or product. One good posture LCA takes in a system study is to give holistic LCIA method and its calculations (environmental impacts) are based on definite factors. This helps to speed up the analysis as well as simplify the system studied.

There are two approaches in LCIA: process-oriented approach (midpoints) and damage-oriented approach (endpoints). The life cycle assessment expert can use either of them for evaluation [37]. Midpoints and endpoints are characterization models that indicate effects at different levels. In the midpoint approach, flows are categorized into environmental impacts to which they contribute. This approach contains about 18 impact categories: global warming, stratospheric ozone depletion, ionizing radiation, ozone formation, terrestrial acidification, freshwater eutrophication, marine eutrophication, terrestrial ecotoxicity, freshwater ecotoxicity etc. [38]. This approach helps to simplify numerous flows by streamlining them into few prevalent environmental impacts. Endpoint approach on the other hand classifies impacts into 22 environmental impact categories and thereafter simplifies flow to evaluate impacts at the area of significance to life (AoSL): human health, ecosystem, resources [39]. Although, the midpoint approach gives a cause-effect evaluation right from the emission of substance or usage of resources, endpoint helps to answer the question: why should I worry about these impacts? [40].

ReCiPe, an acronym for the developers: RIVM, Radboud University, CML and PRé Consultants, is the LCIA method that will be adopted in this study; it offers the platform for carrying LCIA using both approaches [37]. The development of ReCiPe was mainly as a result of the need to harmonize the midpoint and endpoint methods and consequently break the barrier of the selection of LCIA method in LCA model [38].

When midpoint LCIA method is used for analysis, the result presents 18 impact categories, which covers several impacts while endpoint on the other hand presents the 22 impact categories. These impacts are later classified in three damage categories in the AoSL which are human health, resources and ecosystem based on their effects; giving a slightly easy result analysis. In human health category, ReCiPe uses the disability-adjusted life years (DALY) which means the years of life expended or the years of damage to life as a result of environmental impacts. Ecosystem damage category is measured by species/yr.; this denotes species lost in a year due to emissions to the environment, water body, etc. and the resources damage is based on economic loss due to marginal increase in costs as a result of scarcity emerging from resource extraction. It is measured using USD (2013) [38, 41, 42].

ReCiPe uses a cultural theory as 3 models are used to qualify 3 basic assumptions and consideration [43]. These are the Individualist (I), the Egalitarian (E) and Hierarchism (H). The Individualist (I) considers the short-range impact because of the greatest significant chemicals. Egalitarian (E) is established on preventive measure that takes into consideration the long-term perception and implied risk.
